Physics can someone help me with it?

I have a box I want to make the sides like being floppy like real life i named them PhysicsPart also they fall off cause i cant weld it so it wont work can someone tell me step by step how to do it?

You should use a hingeconstraint:

Ill try making one and send it to you give me a minute

here you go:
Box.rbxm (5.5 KB)